Portable apparatus and method for detection of methylxanthine chemical species

Abstract

A portable apparatus for detecting the presence of at least one methylxanthine chemical species such as caffeine or theophylline in a beverage comprises a first portion comprising an effective concentration of phosphodiesterase enzyme, a second portion comprising cyclic AMP, and means for indicating inhibition of degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species. A method for determining the presence of at least one methylxanthine chemical species in a beverage comprises contacting at least one test portion of the beverage with effective concentrations of at least one phosphodiesterase enzyme and cyclic AMP, and further contacting the test portion with means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species. The apparatus and method are advantageous in that they provide a simple and effective means of determining whether methylxanthine chemical species such as caffeine or theophylline are present in coffee, tea and other beverages.

We claim: 
     
       1. A portable apparatus for detecting the presence of at least one methylxanthine chemical species in a beverage comprising: (a) a first portion comprising phosphodiesterase enzyme;   (b) a second portion comprising cyclic AMP;   (c) a third portion for receiving a sample of said beverage prior to said sample contacting the phosphodiesterase and the cyclic AMP; and   (d) means for indicating inhibition of degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species.   
     
     
       2. The apparatus of claim 1, wherein the apparatus additionally comprises covering means for protecting the apparatus prior to use. 
     
     
       3. The apparatus of claim 1, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species is means responsive to a change in concentration of hydrogen ions in the beverage. 
     
     
       4. The apparatus of claim 3, wherein the means responsive to a change in concentration of hydrogen ions in the beverage is a calorimetric pH indicator. 
     
     
       5. The apparatus of claim 3, wherein the means responsive to a change in concentration of hydrogen ions in the beverage is a pH-sensitive electrode assembly. 
     
     
       6. The apparatus of claim 1, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species is means for determining the concentration of inorganic phosphate or adenosine released from a two-step reaction wherein in the first step the cyclic AMP forms 5'-AMP in the presence of the phosphodiesterase, and in the second step the 5'-AMP forms said adenosine and inorganic phosphate in the presence of venom. 
     
     
       7. The apparatus of claim 6, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase is a colorimetric means for determining the concentration of the inorganic phosphate. 
     
     
       8. The apparatus of claim 6, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species is means for determining the concentration of the adenosine. 
     
     
       9. The apparatus of claim 1, wherein the phosphodiesterase is contained within a gel matrix. 
     
     
       10. A method for determining the presence of at least one methylxanthine chemical species in a beverage comprising: (a) placing at least one portion of the beverage in a receiving portion of an apparatus, said apparatus additionally comprising a first portion comprising phosphodiesterase enzyme and a second portion comprising cyclic AMP;   (b) contacting said test portion of the beverage with the first and second portions of the apparatus, thereby inhibiting degradation of the cyclic AMP to AMP by the phosphodiesterase due to the presence of any methylxanthine species in the beverage;   (c) contacting the test portion of step (b) with means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species in the beverage; and   (d) correlating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase with the presence of the methylxanthine species in the beverage.   
     
     
       11. The method of claim 10, wherein the methylxanthine chemical species is caffeine. 
     
     
       12. The method of claim 10, wherein the methylxanthine chemical species is theophylline. 
     
     
       13. The method of claim 10, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species is means responsive to a change in concentration of hydrogen ions in the test portion of the beverage. 
     
     
       14. The method of claim 13, wherein the means responsive to a change in concentration of hydrogen ions in the beverage is a colorimetric pH indicator. 
     
     
       15. The method of claim 10, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the methylxanthine species is means for determining the concentration of inorganic phosphate or adenosine released from a two-step reaction wherein in the first step the cyclic AMP forms 5'-AMP in the presence of the phosphodiesterase, and in the second step the 5'-AMP forms said adenosine and inorganic phosphate in the presence of venom. 
     
     
       16. The method of claim 15, wherein the concentration of the inorganic phosphate is determined by calorimetric means. 
     
     
       17. The method of claim 15, wherein the means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase activity due to the presence of the methylxanthine species is means for determining the concentration of said adenosine. 
     
     
       18. The method of claim 10, wherein the test portion is first contacted with the phosphodiesterase, and thereafter contacted with the cyclic AMP. 
     
     
       19. A method for determining the presence of at least one methylxanthine chemical species in a beverage comprising: (a) providing carrying means having phosphodiesterase enzyme and separately having cyclic AMP such that the phosphodiesterase and the cyclic AMP are not initially in physical contact with each other, said cyclic AMP being degradable by said phosphodiesterase, and wherein said degradation is inhibited in the presence of said at least one methylxanthine species, said carrying means additionally having a receiving portion for receiving a sample of the beverage prior to said sample contacting the phosphodiesterase and the cyclic AMP;   (b) providing detecting means for indicating inhibition of the degradation of the cyclic AMP by the phosphodiesterase in the presence of the methylxanthine species;   (c) physically contacting the sample of said beverage and said carrying means such that said phosphodiesterase and said cyclic AMP are physically contacted; and   (d) determining from said detecting means whether said degradation was inhibited, thereby indicating the presence of said at least one methylxanthine species in the beverage.   
     
     
       20. The method of claim 19, wherein the methylxanthine chemical species is caffeine. 
     
     
       21. The method of claim 19, wherein the methylxanthine chemical species is theophylline. 
     
     
       22. The method of claim 19, wherein the detecting means is means responsive to a change in concentration of hydrogen ions in the sample. 
     
     
       23. The method of claim 19, wherein the sample is first contacted with the phosphodiesterase enzyme, and thereafter contacted with the cyclic AMP. 
     
     
       24. A method for determining the presence of caffeine in a beverage comprising: (a) placing a test portion of the beverage in a receiving portion of an apparatus, said apparatus additionally comprising a first portion comprising phosphodiesterase enzyme and a second portion comprising cyclic AMP;   (b) contacting said test portion of the beverage with the first and second portions of the apparatus, thereby inhibiting degradation of the cyclic AMP to AMP by the phosphodiesterase due to the presence of any caffeine in the beverage;   (c) contacting the test portion of step (b) with means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase due to the presence of the caffeine in the beverage; and   (d) correlating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase with the presence of said caffeine in the beverage.   
     
     
       25. A method for determining the presence of caffeine in a beverage comprising: (a) providing carrying means having a phosphodiesterase enzyme and separately having cyclic AMP such that the phosphodiesterase and the cyclic AMP are not initially in physical contact with each other, said cyclic AMP being degradable by said phosphodiesterase, and wherein said degradation is inhibited in the presence of any caffeine in the beverage, said carrying means additionally having a receiving portion for receiving a sample of the beverage prior to said sample contacting the phosphodiesterase and the cyclic AMP;   (b) providing detecting means for indicating the inhibition of the degradation of the cyclic AMP by the phosphodiesterase in the presence of said caffeine;   (c) physically contacting said phosphodiesterase, said cyclic AMP, and said detecting means by means of said sample of said beverage; and   (d) determining from said detecting means whether said degradation was inhibited, thereby indicating the presence of said caffeine in the beverage.